UPHESC Assistant Professor Geology PYQs

Concept: Spreading methods let surface water spread over or into the ground and infiltrate: basins, ditches & furrows, flooding, pits/shafts. Induced recharge instead pumps wells sited near a river/lake so that the lowered water table draws (induces) surface water into the aquifer.

1. Basin, ditch-furrow and pit methods all spread water to infiltrate.
2. Induced recharge works by pumping – an indirect method, no spreading.

Short trick: Induced = pump-induced bank infiltration, not spreading.

Concept: The LGM, when the last (Weichselian/Wisconsin) ice sheets were at their greatest extent and sea level ~120 m lower, was about 26,000–19,000 years ago, centred near 21–22 ka B.P.

1. Holocene (last 11,700 yr) is post-glacial.
2. 110–60 ka is the early part of the last glaciation, not its maximum.
3. 280 Ma is the Permo-Carboniferous (Gondwana) glaciation.

Short trick: LGM ≈ 22 ka; Holocene starts 11.7 ka.

Concept: A metabasite (dolerite/basalt) in the amphibolite facies becomes an amphibolite: hornblende + plagioclase (andesine) ± garnet, epidote.

1. Opx + Cpx + Pl – granulite facies.
2. Chlorite + actinolite + albite (± epidote) – greenschist facies.
3. Lawsonite + glaucophane – blueschist facies.

Short trick: Amphibolite facies → Hornblende + Plagioclase (= amphibolite rock).

Concept: In fractional (Rayleigh) fusion each increment of melt is removed as soon as it forms, so it cannot re-equilibrate with the residual solid; in equilibrium (batch) fusion the melt stays in contact and reacts with the residue until it is extracted.

1. Fractional fusion gives melts that jump from eutectic to eutectic in a phase diagram.
2. 'Differentiated melt' describes a product, not the melting process.

Short trick: Fractional = remove instantly; Equilibrium/Batch = keep together.

Concept: Connate water is water trapped in the pores of sediments at the time of their deposition and isolated from the hydrological cycle for a long time – hence called 'fossil water'.

1. Juvenile (magmatic) water – new water from magma, never in the hydrological cycle before.
2. Meteoric water – derived from precipitation; the bulk of groundwater.
3. Cosmic water – from space (comets/meteorites), negligible.

Short trick: Connate = 'born with' the sediment = fossil water.

Concept: Hydraulic conductivity K = Q/(iA); with Q in m³/day, i dimensionless and A in m², K has the units of velocity – m/day (or m/s, cm/s).

1. m²/day (or m²/s) is the unit of transmissivity T = Kb.
2. m³/s is the unit of discharge Q.

Short trick: K – velocity (m/d); T – m²/d; Q – m³/d.

Concept: A pleochroic scheme (colours for X, Y, Z vibration directions) can be written only for coloured anisotropic minerals; hornblende is strongly pleochroic: X = light yellow-green, Y = green/olive, Z = dark green/blue-green.

1. Quartz and muscovite are colourless in thin section – no pleochroism.
2. Garnet is isotropic (cubic) – cannot be pleochroic.

Short trick: Pleochroic scheme needs colour + anisotropy: hornblende, biotite, tourmaline.

Concept: Three 4-fold axes (along the three crystallographic axes) are characteristic of the holohedral (normal) class of the cubic/isometric system; galena (PbS) is cubic (m3m).

1. Gypsum – monoclinic (one 2-fold axis).
2. Baryte – orthorhombic (three 2-fold axes).
3. Rutile – tetragonal (only one 4-fold axis).

Short trick: 3 × 4-fold axes = cube: galena, halite, fluorite, garnet.

Concept: Indian (Gondwana) coals – which form over 98% of Indian coal – are generally regarded as of drift origin: plant material was transported by rivers and deposited in lakes/basins (Fox, Krishnan).

1. Evidence: high ash content, absence of true seat-earths/underclays with roots, interbanding with sandstones, and great seam thickness with splitting.
2. In-situ (autochthonous) coal, typical of Carboniferous coals of Europe/USA, shows rootlet beds (Stigmaria) below seams.

Short trick: Gondwana coal = drifted (high ash); Euro-American Carboniferous = in-situ.

Concept: Know the crystal system of common minerals.

1. Garnet – cubic (isometric) → (2).
2. Cassiterite (SnO₂) – tetragonal, rutile group → (3).
3. Axinite – triclinic → (4).
4. Orthoclase – monoclinic → (1). Code: 2-3-4-1.

Short trick: Garnet cube, Cassiterite = Rutile-tetragonal, Axinite 'axe' = triclinic, Orthoclase = 'right-angle' cleavage but monoclinic.

Concept: Goldschmidt grouped elements by the phase they prefer in a differentiated Earth/meteorite.

1. Siderophile ('iron-loving': Fe, Ni, Co, Pt, Au) – metallic iron phase → (3).
2. Chalcophile ('copper/sulphur-loving': Cu, Zn, Pb, Ag) – sulphides → (1).
3. Lithophile ('rock-loving': Na, K, Mg, Al, Si) – silicates → (2).
4. Atmophile (N, noble gases, H) – atmosphere → (4). Code: 3-1-2-4.

Short trick: Sidero = iron, Chalco = sulphide, Litho = silicate, Atmo = air.

Concept: In a ductile shear zone strain is heterogeneous: it increases from the margins (low strain, protomylonite) to a maximum at the centre (ultramylonite), which is why foliation curves (sigmoidally) into the zone.

1. (A) True – faults pass downward into ductile shear zones below the brittle–ductile transition.
2. (C) True – from mm-scale to crustal-scale (hundreds of km).
3. (D) True – displacement is accommodated by ductile flow.

Short trick: Shear zone: strain is low at edges, highest in the core – never uniform.

Concept: Pull-apart basins are rhomb-shaped depressions formed at releasing bends or releasing step-overs between en-echelon strike-slip fault segments, where local extension (transtension) occurs.

1. Examples: Dead Sea basin, Death Valley, Salton trough.
2. Restraining bends in the same systems give push-up ridges (compression).

Short trick: Releasing bend → pull-apart; restraining bend → push-up.

Concept: Darcy's law: discharge through a porous medium Q = KiA, where K = hydraulic conductivity, i = hydraulic gradient (dh/dl), A = cross-sectional area.

1. Q = AV is the continuity equation (V = Darcy velocity/specific discharge = Ki).
2. Darcy (1856) derived it from sand-filter experiments at Dijon.

Short trick: Darcy: Q = K·i·A ('Quite Kind i A').

Concept: Discharge is the volume of water passing a section per unit time: Q = A × V = m² × m/s = m³/s (cumec).

1. m/s – velocity (or hydraulic conductivity).
2. m²/s – transmissivity or diffusivity.

Short trick: Discharge = volume/time → m³/s (cumec).

Concept: Typical porosities: clay 40–70%, weathered granite 34–57%, coarse sand 25–40%, but unweathered basalt only about 3–10% (higher only if vesicular/fractured).

1. Clay has the highest porosity yet very low permeability.
2. Crystalline/igneous rocks like fresh basalt have the least primary porosity.

Short trick: Fine sediments – high porosity; fresh crystalline rock – lowest.

Concept: Kimberlite is a volatile-rich (CO₂, H₂O) potassic ultrabasic rock; primary magmatic calcite (carbonate) is a characteristic groundmass mineral, so statement (C) is false.

1. (A) True – high-pressure phases like coesite occur as inclusions in kimberlitic diamonds/xenoliths.
2. (B) True – carrot-shaped diatremes (pipes) narrowing downward into root zones and dykes.
3. (D) True – kimberlite pipes are the primary source of diamonds (Kimberley, Majhgawan-Panna).

Short trick: Kimberlite = olivine + phlogopite + CALCITE (carbonate-rich), diamond-bearing pipe.

Concept: In a binary eutectic system (e.g. diopside–anorthite) the eutectic point gives the lowest temperature of crystallization/melting and the composition at which two minerals crystallize together in fixed proportion.

1. (1) It tells the order and final temperature of crystallization – correct.
2. (2) It fixes the composition/proportion of minerals crystallizing from the melt – correct.
3. (3) Crystal shape and size depend on kinetics (cooling rate, nucleation), not on the equilibrium phase diagram – incorrect.

Short trick: Phase diagram = T + composition; texture (size/shape) = kinetics.

Concept: A water-table contour (equipotential) map shows hydraulic head; groundwater – and dissolved contaminants – flow perpendicular to contours from high to low head, so flow lines drawn on it trace a pollutant back to its source and forward to its destination.

1. Porosity and permeability maps show aquifer properties but not flow direction.
2. Soil maps give only surface material.

Short trick: Flow ⟂ water-table contours, high → low head.

Concept: Slope failure occurs when driving (shear) stress exceeds shear strength; many factors combine.

1. Tectonics – active faults, earthquakes, fractured/sheared rock.
2. Slope angle – steeper slopes raise shear stress.
3. Rainfall – raises pore-water pressure, reduces effective strength (the commonest trigger in the Himalaya).

Short trick: Landslide = steep slope + weak (tectonised) rock + water trigger.